A wild bottlenose dolphin plays with a diver in the ‘green’ waters off the western coast of Ireland. After humans, dolphins have the largest brains in the animal kingdom, relative to body size. Despite this fact, their world is very different than our own and the ways in which they use their brain is fascinating. Dolphins see much of their world acoustically, using echolocation (i.e. sonar) to determine the location of objects and distances. Dolphins also sleep with one half of their brains awake, as they need to be constantly alert for predators and because they are voluntary breathers.
In several locations around the world, dolphins have established residency, and frequently interact with humans.